Biocides provide antimicrobial protection for industrial, personal care, medical and other products and materials. Typically, the biocide has a somewhat limited range with respect to the specific microorganisms it will kill, has some toxicity, and presents some environmental hazard, or a combination of these drawbacks. Thus, it would be useful to find a means to enhance biocidal activity, or extend the range of antimicrobial effectiveness of biocides, without increasing toxicity or the degree of environmental hazard of these compounds.
Certain combinations of pyrithione with other additives to provide a preservative, antibacterial or antifungal efficacy are known in the art. For example, Japanese Kokai 59-(1984)98001 discloses a cut flower preservative comprising pyrithione or a salt thereof, an aliphatic carboxylic acid, and a saccharide. U.S. Pat. No. 4,242,336 discloses an antibacterial and antifungal composition comprising (a) at least one member selected from the group consisting of dehydroacetic acid, sorbic acid and their alkali metal salts and (B) at least one member selected from the group consisting of alkyl(aminoethyl)-glycines having C8 to C16 alkyl groups and their salts, 2-pyridine-thiol 1-oxide (i.e., pyrithione) and its salts, and tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione. However, these references do not disclose the basis for the efficacy of these disclosed combinations, nor do they suggest other antimicrobial combinations. Furthermore, the sorbic acid disclosed in the '336 patent is subject to chemical instability problems, necessitating the use of a stabilizer to inhibit oxidation, such as manganous ion, as disclosed in U.S. Pat. No. 5,354,902.
New combinations of pyrithione with other additives, exhibiting synergistic efficacy over a wide range of use concentrations, without the need for (and preferably in the absence of) any oxidative inhibition stabilizer, would be highly desired by the biocides community, particularly if such compositions also exhibit low toxicity against mammals. The present invention provides several of such combinations.